<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
       
        #text1 {
            color: red;
            font-size: 20px;
        }
        p{
            color: blue;
            font-size: 16px;
        }
    </style>
</head>
<body>
    <!-- id选择器 -->
     <P id="text1">你好</P>
     <p>this is a paragraph</p>

</body>
</html>